Optical waveguide structures for vehicle lighting

ABSTRACT

An optical waveguide for illuminating the interior of a cup holder in a vehicle is disclosed. The waveguide includes a piece of solid material having a ring portion sized and shaped to be received within a cup holder and configured to release light into the cup holder. An input face receives light from a light source. An input portion extends between the input face and the ring portion. The input portion confines light through internal reflection to direct light from the input face to the ring portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Provisional Application Ser. No.60/069,118, “HID DRIVEN FOCUS-LESS OPTICS SYSTEM,” filed Dec. 9, 1997and application Ser. No. 09/009,836, “DISTRIBUTED LIGHTING SYSTEM,”filed Jan. 20, 1998, both of which are incorporated by reference.

BACKGROUND

The invention relates to distributed lighting systems.

Distributed lighting systems distribute light from one or more lightsources in central locations to one or more remote locations. Adistributed lighting system promises several advantages overconventional lighting techniques, including low power consumption,extended life, heat reduction where the light is emitted, and increaseddesign flexibility.

SUMMARY

The invention provides a distributed lighting system (DLS) for use, forexample, in an automobile. Issues associated with incorporating adistributed lighting system into an automobile are discussed by Hulse,Lane, and Woodward in “Three Specific Design Issues Associated withAutomotive Distributed Lighting Systems: Size, Efficiency andReliability,” SAE Technical Paper Series, Paper No. 960492, which waspresented at the SAE International Congress and Exposition, Detroit,Mich., Feb. 26-29, 1996 and Hulse and Mullican in “Analysis of WaveguideGeometries at Bends and Branches for the Directing of Light,” SAETechnical Paper Series, Paper No. 981189, which are incorporated hereinby reference.

A practical distributed lighting system for an automobile must addresssize, efficiency, and reliability issues. To this end, an implementationof the invention employs focus-less optics components, such as collectorelements and waveguides. These components are inexpensive tomanufacture, since they can be formed from plastic (acrylic, forexample) in an injection molding process. In addition, they have highcollecting efficiency and are very compact. For example, a collectorelement may be smaller than one cubic inch (16.4 cubic centimeters).Components that must handle high heat levels (e.g., components areplaced in proximity to the light source) may require a ventilationsystem or may include portions formed from heat resistant materials,such as glass or Pyrex™.

The DLS may incorporate different types of optical waveguide structuresto distribute light throughout the vehicle, including joints, elementswith epoxy coatings, pinched end collector portions, integratedinstallation snaps, integrated input optics and integrated outputlenses. The DLS may also include waveguide structures to provideillumination to portions of the vehicle interior, including cup holders,assist grips, and storage pockets.

In one aspect, generally, an optical waveguide for illuminating theinterior of a cup holder in a vehicle is formed from a piece of solidmaterial. The solid material has a ring portion that is sized and shapedto be received within a cup holder and that releases light into the cupholder. An input face receives light from a light source. An inputportion extends between the input face and the ring portion, confineslight through internal reflection, and directs light from the input faceto the ring portion.

Embodiments may include one or more of the following features. The ringportion may define an inner circumference and may release light aroundthe inner circumference. The ring portion may have a protruding angledportion around the inner circumference that directs light down toward abottom portion of the cup holder. The upper surface of the angledportion may be stippled. An upper surface of the angled portion may becovered with an opaque material. The ratio of an inner radius of thering portion to the width of the ring portion may be greater than orequal to 3:1.

The ring portion may include a first arm and a second arm that define agap in the inner circumference. The second arm may have a smallercross-section and a smaller length than the first arm. The ring portionmay have a web portion that extends between the first and second arms.The web portion may release light along its edge. The ring portion mayinclude a tab that extends from the inner circumference between thefirst and second arms. The tab may have a rectangular cross-section andmay curve toward the bottom of the cup holder. The tab may have achamfered leading edge.

The optical waveguide described above may be included in an illuminatedcup holder having a bottom surface. A side wall may extend from thebottom surface and define a volume shaped and sized to receive a cup. Arim may be positioned around the upper edge of the side wall.

In another aspect, an optical waveguide illuminates the inside of anassist grip in a vehicle. The waveguide is a piece of solid materialhaving an illumination portion with an inner surface and an outersurface. The illumination portion is sized and shaped to be receivedwithin a channel along the length of the assist grip and releases lightfrom the inner surface. An input face at one end of the illuminationportion receives light from a light source.

Embodiments may include one or more of the following features. The innersurface may be stippled. The ratio of the inner radius of a bend to thewidth of the waveguide may be greater than or equal to 3:1. Thewaveguide may have snaps extending from the outer surface that hold theillumination portion in place within the channel. A lens positionedadjacent to the light source may focus light from the light source toform a courtesy light. An illuminated assist grip for a vehicleincluding the waveguide described above also may have a handle portionformed of solid material, a channel formed along the length of thehandle and a light source receptacle configured to receive a lightsource.

In another aspect, an optical waveguide for a vehicle door illuminatesan area beneath the vehicle. The door has a bottom surface that meets afloor surface of the vehicle when the door is closed. The waveguideincludes a door portion positioned inside the door and extending to thebottom surface of the door. A floor portion extends from the floorsurface to the underside surface of the vehicle. The door portion andthe floor portion meet when the door is closed so that light may passthrough the door portion and the floor portion to illuminate the areabeneath the vehicle. Embodiments may include a branch that extends fromthe door portion to an interior surface of the door to illuminate theinterior of the vehicle.

In another aspect, an illuminated storage pocket for a vehicle has asurface that defines a storage volume and a rim around an edge of thesurface. A waveguide formed from a piece of solid material has anillumination portion that has an inner surface and an outer surface. Theillumination portion is received within a channel along the rim of thestorage pocket and releases light from the inner surface. An input faceat one end of the illumination portion receives light from a lightsource.

Embodiments may include one or more of the following features. The innersurface of the waveguide may be stippled. The waveguide may includesnaps that extend from the outer surface and hold the illuminationportion in place within the channel.

In another aspect, an optical waveguide includes a first and a secondpiece of solid material. The first piece has a transmission portion witha rectangular cross-section. The end of the transmission portion isconvex in one dimension. The second piece has a transmission portionwith a rectangular cross-section. The end of the transmission portion isconcave in one dimension. The end of the first piece and the end of thesecond piece form an interface between the first and second pieces.

Embodiments may include one or more of the following features. Thewaveguide may include a third piece of solid material having atransmission portion with a rectangular cross-section. The end of thetransmission portion may be concave in one dimension. The end of thethird piece and the end of the first piece may form an interface betweenthe first and third pieces. A band may hold the first, second and thirdpieces together.

The waveguide may include a third piece of solid material having atransmission portion with a rectangular cross-section. The end of thetransmission portion may be convex in one dimension. The end of thethird piece and the end of the second piece form an interface betweenthe second and third pieces. A band may hold the first, second and thirdpieces together.

In another aspect, an optical waveguide accepts light from a lightsource and transmits the light. The waveguide is formed from a piece ofsolid material having an input face, a transmission portion and an endportion between the input face and the transmission portion. Across-sectional area of the end portion gradually decreases from thetransmission portion to the input portion.

Embodiments may include one or more of the following features. The endportion may have planar sides angled from a longitudinal axis of thetransmission portion. The angle formed between the sides and thelongitudinal axis may be about 5°. The end portion may increase theacceptance angle of the waveguide. A lens portion may be formed on theinput face.

In another aspect, an optical waveguide has integrated installationelements. The waveguide includes first and second sections. The firstsection has an input face, an output end and a transmission portionextending from the input face to the output end. A key is positioned onthe output end and mates with a socket of the second section. The secondsection has an input face, an output end and a transmission portionextending from the input face to the output end. A socket is positionedon the output end and mates with the key of the first section.

Embodiments may include one or more of the following features. Thewaveguide may include a snap positioned on the transmission portion ofthe first or second section. The snap may mate with an installationfitting of a vehicle. The outer surface of the waveguide may be coveredwith epoxy.

In another aspect, an optical waveguide has integrated installationelements. The waveguide includes first and second sections. The firstsection has an input face, an output end and a transmission portionextending from the input face to the output end. A claw is positioned onthe output end and mates with a detent of the second section. The secondsection has an input face, an output end and a transmission portionextending from the input face to the output end. A detent is positionednear the output end and mates with the claw of the first section.

Embodiments may include one or more of the following features. A snapmay be positioned on the transmission portion and may mate with aninstallation fitting of a vehicle. An outer surface of the waveguide maybe covered with epoxy.

In another aspect, an optical waveguide has an output element forproviding illumination in a vehicle. The waveguide includes an inputface and a transmission portion extending from the input face. Thetransmission portion widens at an end to form an output element having aconvex lens at the end of the output element. The output element may beformed to leave an air gap between the lens and the end of thetransmission portion.

Other features and advantages will be apparent from the followingdetailed description, including the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a vehicle distributed lighting system withhybrid lighting subsystems.

FIG. 2 shows a hybrid headlamp subsystem.

FIG. 3 shows a hybrid headlamp subsystem with a movable lens.

FIGS. 4A-4D show headlamp beam forming structures.

FIG. 5 shows a light source with a diffusion grating.

FIGS. 6A-6F show waveguide outputs modulated with electromechanical orliquid crystal light valves.

FIG. 7 shows a hybrid tail light subsystem.

FIG. 8 shows a compact incandescent cartridge.

FIGS. 9A and 9B show a waveguide output bend for a tail light.

FIGS. 10A and 10B show a combination security/puddle light.

FIGS. 11A-11F show various embodiments of a cup holder illuminationcomponent.

FIG. 12A is a rear view of a waveguide installed in a handgrip.

FIG. 12B is a cross-section view of a waveguide and light sourceinstalled in a handgrip.

FIG. 12C shows a waveguide with integrated snaps for installation into ahandgrip.

FIG. 13 is a cross-section view of an optical waveguide.

FIGS. 14A and 14B are side and bottom views of a waveguide joint.

FIG. 15 is a cross-section view of an epoxy-coated optical waveguide.

FIGS. 16A-16C are cross-section views of non-tapered and taperedwaveguide inputs.

FIGS. 17A and 17B are cross-section views of waveguide sections havingintegrated installation components and an integrated output structure.

FIG. 18 shows a leaky waveguide bend and focusing lens.

FIGS. 19A and 19B show cross-section views of optical manifolds.

DESCRIPTION

Referring to FIG. 1, a vehicle distributed lighting system (DLS) 100includes hybrid headlamp subsystems 105, turn signal subsystems 110 and140, and hybrid tail light subsystems 130. The hybrid headlampsubsystems 105 provide primary forward illumination for the vehicle. Theheadlamp subsystems 105 are also light sources for other exteriorlights, such as front turn signals of the subsystems 110 and sidemarkers 115, as well as interior lights, such as dashboard lights 120and dome lights 125. These other lights are connected to the headlampsubsystems by optical waveguides 135. Similarly, the tail lightsubsystems 130 provide light for rear turn signals 140 and a center highmounted stop light (CHMSL) 145. The subsystems of the DLS areinterconnected so that the light source of one subsystem serves as aredundant light source for another subsystem.

The DLS incorporates different types of optical waveguide structures todistribute light throughout the vehicle. These include joints, elementswith epoxy coatings, pinched end collector portions, integratedinstallation snaps, integrated input optics and integrated outputlenses. The DLS also includes waveguide structures to provideillumination to portions of the vehicle interior, including cup holders,assist grips, and storage pockets.

FIG. 2 illustrates a hybrid headlamp subsystem 105. The subsystemincludes a light source 205 that may be implemented using, for example,a high-intensity discharge (HID) lamp. Light produced by the lightsource 205 is collected by a reflector 210 and directed through a lens215 to provide the primary forward illumination for the vehicle. Thereflector may be implemented as a parabolic or complex reflector.

The hybrid headlamp subsystem 105 provides both high beam and low beamillumination. To this end, the subsystem may employ a number ofdifferent beam forming techniques, as shown in FIGS. 3-5. For example,FIG. 3 shows a simple Fresnel lens 305 that is moved by an actuator 310between a high beam position and a low beam position. The movement ofthe lens 305 shifts the position of the “hot spot” (i.e., the area ofmost concentrated light) of the headlamp beam in the far field betweenthe appropriate positions for the high and low beams. Other portions ofthe beam also will shift as the lens moves. In addition to lens, otheroptical elements, such as wedges, may be used to control the beampattern.

FIGS. 4A-4D show the use of a solid molded plastic form 405 (FIGS.4A-4C) or a bundle of plastic or glass fibers 410 (FIG. 4D) to generatea desired headlamp beam pattern. Light from light source 205 passesthrough the form 405 or bundles 410 and then passes through a focusinglens 415. The shape of the output end 420 of the solid form or bundles,in conjunction with the properties of the focusing lens, determines thebeam pattern in the far field. To increase light collection efficiency,the shape of the input end 425 of the solid form may be configured toact as a collector element to receive light from a light source. Areflector 215 may also be used to control the beam pattern, as in FIGS.2 and 3. FIGS. 4A-4C show dimensions in mm [inches] of a thicknessprofile that might be used to achieve a desired beam pattern. Similarly,the bundle of fibers can be formed into a desired profile. As with theimplementation shown in FIG. 3, the lens 305 may be moved to shift thehot spot of the beam between high beam and low beam positions.

FIG. 5 shows the use of a diffraction grating 500 to control theheadlamp beam pattern (the diffraction grating may also be used forother lighting functions, such as stop lights and turn signals). Thediffraction grating 500 includes essentially transparent material thathas a series of ridges 505 on its surface. The width 510 of the ridgesis approximately equal to the wavelength of the light produced by thelight source 205. A portion 515 of the light passing through thediffraction grating 500 is reflected back into the light source, withthe size of the portion depending upon the exit angle (θ) of the lightray. Most of the light 520 travelling in a direction close toperpendicular (θ=0°) passes through the grating undisturbed. By limitingthe exit angle (θ) of the headlamp illumination, the grating 500 mayprovide, for example, a more focused headlamp beam in the far field. Thegrating 500 may be used alone or in conjunction with lenses 305, solidforms 405 or fiber bundles 410 described above to provide a desiredheadlamp beam pattern.

In addition to providing the primary forward illumination, the lightsource 205 acts as a light source for other parts of the system. Asshown in FIG. 2, waveguides 135 having collector elements 220 at theirends are positioned close to the light source 205 to receive light andtransmit the light to other locations in the vehicle, such as to provideturn signals, interior lighting, fog lights, and side markers. Thewaveguides 135 may also carry light to other lighting subsystems toprovide redundancy, such as the opposite side headlamp or the taillights. The number of collector elements 220 may be increased asnecessary to supply light for other lighting functions. The collectorelements 220 may be glass rods (such as Pyrex) with ends that arepolished so as to be faceted or pinched. The pinched ends increase theacceptance angle of the collector element.

FIG. 2. shows a waveguide 225 that carries light from the source to aside marker light 115. The waveguide 225 may include colored plasticfilters 230 to provide a desired output color (e.g., amber) for the sidemarker 115. This configuration eliminates the need for an electricalconnection and light bulb in the side marker 115.

Another waveguide provides light to the turn signal subsystem 110.Alternatively, the turn signal subsystem 110 may include an independentlight source and may use the input from the headlamp subsystem 105 forredundancy.

As shown in FIGS. 6A-6D, some implementations of the turn signalsubsystem use an electromechanical shutter 605 (FIGS. 6A and 6B) whileothers use a liquid crystal light valve (LCLV) 610 (FIGS. 6C and 6D) tomodulate the light produced by the turn signal. A plastic colored filterprovides amber color for the turn signal. The use of a colored filtereliminates the need for light bulbs enclosed in cadmium-doped glass.

The electromechanical modulator 605, as shown in FIGS. 6A and 6B,includes an opaque shutter 615 that is moved between an ON (FIG. 6A) andOFF (FIG. 6B) position by a solenoid 620. In the ON position, theshutter 615 is moved away from the illumination path, so thatessentially all of the light is transmitted. In the OFF position, theshutter 615 blocks the illumination path so that no light istransmitted. The use of an electromechanical modulator 605 with anamber-colored plastic filter provides a desirable aesthetic effect(i.e., the turn signal appears amber when ON but has no color when OFF).

The LCLV illustrated in FIGS. 6C and 6D has no mechanical components.This increases the reliability of the LCLV relating to systems thatinclude mechanical components. The LCLV 610 has two states. In the OFFstate (FIG. 6D) the LCLV 610 reflects or scatters most of incidentlight. In the ON state (FIG. 6C) the LCLV 610 becomes largelytransparent (i.e., greater than 80% of incident light passes through theLCLV). The ratio of the light transmitted in the ON state relative tothe light transmitted in the OFF state (i.e., the contrast ratio) isapproximately 5:1, which meets SAE requirements for a turn signal. Acontrast ratio of 5:1 also meets the SAE requirements for stop lightsused as turn signals. An infrared reflecting mirror (not shown) may beused to shield the LCLV from infrared energy from the source, therebyincreasing the expected life of the LCLV.

As shown in FIGS. 6E and 6F, LCLV modulators 610 may be combined withdiffraction gratings 500 to improve the contrast ratio and achieve adesired beam pattern. As discussed above, light from the light source(waveguide 135) is scattered when the LCLV is OFF (FIG. 6F). Thediffraction grating 500 lessens the amount of forward scattered lightthat is emitted. Focusing optics, such as lenses 630, may also be usedto provide further beam pattern control.

Referring again to FIG. 1, waveguides also may carry light from theheadlamp subsystem to other subsystems that have their own lightsources, such as the opposite headlamp subsystem (waveguide 137) or thecorresponding tail light subsystem (waveguide 138), to provide lightsource redundancy. When redundancy is employed and, for example, one ofthe headlamps fails, light from the operational headlamp will dimlyilluminate the failed headlamp. This is safer for the operator of thevehicle than having only one operational headlamp. Redundancy also maybe used to reduce the effects of failure of other lighting components.For example, an incandescent PC bulb may be used as a source for trunklighting and may be connected to provide redundancy to interior readinglights.

The tail light subsystems 130 of FIG. 1 operate similarly to theheadlamp subsystems. As shown in FIG. 7, a tail light subsystem 130 hasa light source 705 that provides primary rear illumination through alens 710. The light source 705 may be a HID lamp or another type oflighting source, such as an incandescent lamp, since the lightingrequirement (in lumens) generally is less than the requirement for aheadlamp. In general, an incandescent source is significantly lessexpensive than an HID source.

A compact incandescent cartridge 800, such as shown in FIG. 8, may beemployed as the light source 705. The cartridge 800 includes a housing805 having reflective, heat-dissipating interior surfaces 810. Anincandescent bulb 815 is positioned in the center of the housing 805.Waveguide collector elements 220 are positioned around the light source.The incandescent cartridge 800 has a compact size, stays cool, andreduces lamp placement error, which increases efficiency. In addition,construction of the waveguide collector elements 220 from injectionmolding is easy and inexpensive. The cartridge 800 or similarincandescent sources may also be used as light sources elsewhere in theDLS, depending on lighting requirements. In addition, networks ofcartridges 800 or incandescent sources may be interconnected to provideredundant light sources for interior or exterior lighting functions inthe DLS.

Referring again to FIG. 7, waveguide collector elements 220 in the taillight subsystem are positioned close to the source 705 to receive lightand transmit the light to other lighting elements, such as the rear turnsignals 140, backup lights 150, and center high-mounted stop light(CHMSL) 145. A combination stop/rear turn signal light may be modulatedwith a LCLV 610, as discussed above with respect to the forward turnsignals. The backup lights 150 and CHMSL 145, however, are modulatedwith electromechanical shutters 615, since they must be completely darkin the OFF mode.

The rear turn signals subsystems 140 also may be implemented in themanner shown in FIGS. 9A and 9B. In particular, a waveguide section 900may be used to provide a desired beam pattern for the rear turn signal.Light from a collector element 220 or an independent light source isreceived at the input 910 of the waveguide section 900 and is internallyreflected by the surfaces of the waveguide as it propagates. Thewaveguide 900 includes a bend 920 immediately prior to the output 930.The outer surface of the bend 920 is s-shaped, which changes thedistribution of light across the output surface 930 and hence the farfield beam pattern of the turn signal. As an example, FIG. 9B showsdimensions in mm [inches] of a waveguide 900 that might be used toprovide a desired beam pattern.

The DLS also may be used to provide other lighting functions. Forexample, a waveguide 1000 may be installed in the door 1005, as shown inFIGS. 10A and 10B, to provide a security/puddle light. The waveguide1000 runs from a light source, such as the hybrid headlamp subsystem 105(FIG. 1), to the bottom edge 1010 of the door 1005. A waveguide branch1012 may be used to implement a interior door light. When the door 1005is closed, as in FIG. 10A, a door waveguide section 1015 connects to awaveguide 1020 that passes through the floor 1025. The floor waveguidesection 1020 provides a security light that illuminates the area 1030underneath the vehicle. When the door 1005 is open, as in FIG. 10B, thedoor waveguide 1015 provides a puddle light that illuminates the ground1035 between the open door and the vehicle. The bend 1040 in the doorwaveguide section 1015 may have a bend angle (θ_(B)) of, for example,20°. The bend 1040 helps to direct the output of the waveguide 1000 tothe desired area. Alternatively, the security/puddle light may beimplemented as a hybrid subsystem that has an independent light source.The independent light source may directly provide interior lighting forthe vehicle in addition to being connected to the waveguide 1000 as alight source for the security/puddle light.

Another waveguide carries light from hybrid headlamp subsystem to theinterior of the vehicle to provide, for example, dashboard lighting,dome lights, and reading lights. Waveguides also provide unique,aesthetically pleasing lighting effects for certain interior structures,such as cup holders, map pockets, and assist grips.

For example, as shown in FIGS. 11A and 11B, a ring-shaped waveguideelement 1100 may be installed under the lip 1105 of a cup holder 1110.Although the shape of the waveguide 1100 in FIGS. 11A and 11B iscircular, any shape may be used depending upon the shape and size of thecup holder 1110. The efficiency of the waveguide may be improved byselecting a ratio of the inner radius (r) of the waveguide relative tothe width (w) of the waveguide. For example, a waveguide with an innerradius to waveguide width ratio (r/w) of 3:1 will lose less light than aratio of 1:1 or 0.1:1.

The waveguide 1100 may have a protruding, angled upper region 1115 toreflect and/or transmit light downward toward the bottom 1120 of the cupholder 1110. The upper surface 1125 of the angled portion 1115 may bestippled and may be covered with a layer of opaque material to preventleakage of light in the upward direction. A small incandescent bulb 1130at the input 1135 of the waveguide is used as a source. Light enteringthe input 1135 is transmitted to the ring-shaped portion 1136 of thewaveguide 1100 via an input portion 1137 that is tangentially connectedto the ring-shaped portion 1136. A colored filter 1145 may be placedbetween the source 1130 and the input 1135 to achieve a desiredillumination color. When illuminated, the interior 1140 of the cupholder 1110 glows faintly so as not to interfere with the driver'svision. The glowing illumination allows the occupants of the vehicle todiscern the location of the cup holder 1110. Light for the waveguide1100 also may be provided by a waveguide 135 connected to one of thelighting subassemblies.

Another embodiment of the cup holder illumination waveguide 1100 isshown in FIGS. 11C-11D. These “wishbone” shaped waveguides 1100 areconfigured for cup holders having a gap 1150 to accommodate a mughandle. Light for the waveguide 1100 enters the input 1135 and is splitessentially equally to the two arms 1155 of the wishbone. The split inthe waveguide 1100 may lead to a dark area in the illumination of thecup holder. Therefore, as shown in FIG. 11C, a web portion 1160 isincluded between the two arms 1155. The web portion is thinner than therest of the waveguide 1100 and provides additional illumination to theportion of the interior 1140 of the cup holder directly beneath thesplit in the wishbone.

Alternatively, as shown in FIG. 11D, a tab 1165 that is thinner than therest of the waveguide 1100 may extend downward from the split to reflectand/or transmit light toward the bottom of the cup holder. The tab 1165has a generally rectangular cross-section and curves downward toward thebottom 1120 of the cup holder. As shown in FIG. 11E, the tab 1165 mayhave a chamfered leading edge 1170.

Yet another embodiment of the cup holder illumination waveguide 1100 isshown in FIG. 11F. As in the previous embodiment, the waveguide 1100 isconfigured for cup holders having a gap 1150 to accommodate a mughandle. Light enters the input 1135 and is split unequally between aprimary arm 1175 and a secondary arm 1180. The secondary arm has asmaller cross-section, (i.e., is thinner and narrower than the primaryarm 1175. Since the secondary arm 1180 is shorter than the primary arm1175, there is less loss along its length. The smaller cross-section ofthe secondary arm 1180 allows less light to enter the secondary arm,which balances the light in the two arms 1175 and 1180 provides uniformillumination around the circumference of the cup holder.

Similar structures may be used in the interior of a map pocket or, asshown in FIGS. 12A-12C, along the interior surface 1205 of a assist grip1200. A length of waveguide 1210 is installed along the inner surface1205. The waveguide includes bends 1212 at the ends to conform to theshape of the assist grip. A small incandescent bulb 1215 provides alight source. The bulb may be used in conjunction with a lens (notshown) to provide a courtesy light. Alternatively, the assist grip 1200may be connected by a waveguide to another light source in the DLS. Asshown in FIG. 12C, the waveguide 1210 may be formed with snaps 1220 and1225 to make installation into the assist grip 1200 easier.

Different types of waveguide structures may be used in the DLS totransmit light from the sources to the lighting outputs. A basicwaveguide, as shown in FIG. 13, may be formed from optically transparentmaterial such as acrylic or glass. If the waveguide is formed fromacrylic or a similar material, it can be manufactured using an injectionmolding process. The manufacture of waveguide elements using injectionmolding results in very low manufacturing costs compared to fiberoptics. In addition, molded acrylic waveguide elements are more rigidthan fiber optics, can be installed by robots, and generally do notrequire maintenance, waveguide elements can also achieve much smallerbend radii than fiber.

As shown in FIG. 13, a light ray 1305 entering the input face 1310proceeds through the waveguide 1300 until the light ray 1305 reaches anouter surface 1315 of the waveguide 1300, i.e. an interface between thematerial of the waveguide 1300 and air. At the outer surface 1315, lightis reflected in accordance with Snell's law. If the angle of incidence(θ_(i)) of the light ray 1305 at the outer surface 1315 is less than athreshold referred to as the critical angle (θ_(c)), then the light ray1305 is reflected internally, with no light escaping. This phenomenon isknown as total internal reflection. The critical angle depends on theindex of refraction of the material of which the waveguide is composedrelative to that of the material surrounding the waveguide, (e.g., air).For example, if the waveguide were made from acrylic, which has an indexof refraction of approximately 1.5, and surrounded by air, the criticalangle, θ_(c), would be:

θ_(c)=arcsin(n _(a) /n _(b))=arcsin(1/1.5)=41.8

where n_(a) is the index of refraction of air (1.0) and n_(b) is theindex of refraction of acrylic (1.5).

Referring to FIGS. 14A and 14B, a waveguide joint 1400 may be used todistribute light in the DLS. For example, the joint may be used toprovide light to a door of the vehicle. The waveguide joint 1400 has atrunk section 1405 with a convex curved end 1410. Branch sections 1415having convex curved ends 1420 adjoin the trunk section 1405. The branchsections may be held in place by a plastic band 1425 surrounding thejoint region or by epoxy or snaps. Light input to the trunk section 1405is essentially split among the branches 1415. The branches 1415 may bepositioned to carry light to different sections of the vehicle. It isalso possible to reconfigure the branches 1415 in the event of designchanges. Epoxy that has an index of refraction approximately equal tothat of the waveguide, i.e., that is index-matched, may be used to holdthe branches 1415 in place. The joint 1400 may have only a single branch1415 that is used to change the direction of the trunk 1405 or toprovide a hinged connection. A hinged connection using the joint 1400may be installed, for example, in a car door. Index-matched fluid may beused to lubricate and reduce discontinuity at the interface between thetrunk 1405 and the branch 1415, which will reduce the loss through thejoint 1400.

FIG. 15 shows a waveguide core 1500 encased in a layer of epoxy 1505.The epoxy coating 1505 may be applied by dipping the waveguide core 1500(which may be formed, for example, from acrylic) in a reservoir of epoxyand allowing the coating to dry. The epoxy 1505 has a lower index ofrefraction than the waveguide 1500, so that most of the light rays 1510passing through the waveguide core 1500 are internally reflected at theacrylic/epoxy interface 1515. A portion of the light rays are reflectedat the outer epoxy/air interface 1520. The distribution of light in thewaveguide peaks at the center of the waveguide and diminishes toward theedges of the waveguide. Overall, a significant portion of the light isconfined within the waveguide core 1500 and only a small portion of thelight reaches the outer epoxy/air boundary 1520.

The epoxy coating 1505 offers several advantages compared to an uncoatedwaveguide. For example, contaminants on the surface of an uncoatedwaveguide can cause light at the waveguide/air interface to be scatteredand transmitted outside of the waveguide instead of being internallyreflected, which increases loss in the uncoated waveguide. The epoxylayer 1505 increases the distance between the contaminants and thewaveguide core 1500, which reduces the amount of light that reaches thewaveguide/air interface. In addition, plastic coatings can be applied tothe outside surfaces 1520 of the epoxy layer, and clamps and otherfixtures can be attached to the outside surfaces 1520 with minimaleffect on light transmission through the waveguide 1500. One also coulduse a waveguide formed from polycarbonate (which has an index ofrefraction of 1.58) with an outer coating of epoxy (which has an indexof refraction of 1.4). Alternatively, one could use a waveguide having aglass core and an outer coating having a lower index of refraction.

As shown in FIGS. 16A-C, a waveguide 1600 may have a pinched end thatacts as a collector element 1605. The collector element 1605 increasesthe acceptance angle (α) of the waveguide 1600 and thereby increaseslight collection efficiency. The end of the waveguide 1600 may bepinched in two dimensions to form an essentially trapezoidally shapedcollector element 1605. The collector element 1605 may be formed on theend of a waveguide 1600 having a rectangular or round cross-section.

For example, FIG. 16A shows a waveguide 1610 without a pinched end. Ifthe critical angle (θ_(c)) of the waveguide is 45°, the acceptance angle(α) will also be 45°. Light 1615 from a light source 1620 entering thewaveguide 1610 at an angle greater than 45° will exit the waveguide 1610rather than being reflected at the outer surface 1625. A waveguide 1600having a pinched end, as shown in FIG. 16B, may have an acceptance angle(α) greater than the critical angle (θ_(c)). Assuming θ_(c)=45° and theinclined walls 1630 of the waveguide are inclined at an angle of 5° oneach side, then the acceptance angle (α) will be 50°. As shown in FIG.16C, the pinched end of the waveguide 1600 may be formed so that anexcess of material at the tip of the waveguide 1600 bulges outward toform a lens 1635 with a desired focal length. The lens 1635 focusesreceived light, further increasing the acceptance angle of the waveguide1600.

The waveguides may be formed as a set of standard components that may beeasily interconnected and used as building blocks for differentapplications. For example, FIG. 17A shows waveguides 1700 and 1705having integrated installation elements, such as snaps 1710 and detents1715. Snaps 1710 can be formed during the injection molding of thewaveguide 1700 and provide a convenient means for securing the waveguide1700 within the vehicle. The snaps are sized and angled to minimizelight loss through the snap. For example, the snap may form a 60° anglewith the waveguide (toward the direction that light is travellingthrough the waveguide). The vehicle may have brackets to receive thesnaps 1710 or a screw may be inserted into a snap 1710 to secure thewaveguide to a mounting surface. The detents 1715 enable the waveguide1700 to be securely connected to another waveguide 1705 having anintegrated claw structure 1720. Each waveguide may be formed with adetent 1715 at one end and a claw structure 1720 at the other.

FIG. 17B shows waveguides with integrated connection elements. Awaveguide 1740 may have a key 1745 formed at one end. The key 1745 isconfigured to mate with a socket 1750 of another waveguide 1755. Theseconnection elements may cause a loss of approximately 4% at theinterface, however, the connection elements increase the ease with whichwaveguide components can be installed. Index-matched epoxy or fluid maybe used at the interface to secure the connection and reduce losses.

In addition to the installation and connection elements, the waveguide1700 widens at one end into an output element 1725 having a convexcurved surface 1730. The curved surface 1730 of the output element 1725essentially acts as a lens to provide a desired light outputcharacteristic. The output element 1725 may form an illumination elementfor the vehicle, e.g., a courtesy light in the door of a vehicle. Aportion of the widened waveguide end may be eliminated, leaving an airgap 1735, while maintaining desired output characteristics. The air gap1735 decreases the weight and cost of the waveguide 1700.

Another configuration for an output element is shown in FIG. 18. Awaveguide 1800 has a bend 1805 that is configured to allow a portion ofthe light travelling in the waveguide to escape at the bend 1805. A lens1810 may be used to focus the light to form a desired beam pattern. Theamount of light released at the bend 1805 can be controlled bydetermining the inner radius (r) of curvature of the bend 1805 relativeto the width (w) of the waveguide 1800. For example, a bend with a innerbend radius to waveguide width ratio (r/w) of 3:1 will lose less than 5%of the light in the bend. A bend ratio of 1:1 will result in a loss ofapproximately 30-35%, and a bend ratio of 0.1:1 will result in a loss ofapproximately 65-70%. Not all of the light released at the bend entersthe lens, however the amount of light entering the lens will beproportional to the amount of light released at the bend.

An optical manifold 1900, as shown in FIGS. 19A and 19B, is anotheruseful building block for a DLS. Light enters the optical manifold 1900through one or more inputs 1905 and is split to one or more of theoutput arms 1910. Alternatively, light may enter through one or moreoutput arms 1910 and exit through the inputs 1905. The output arms 1910may branch off at multiple points from the optical manifold in multipledirections to direct light to other subsystems of the DLS in variouslocations within the vehicle. The size of the output arms 1910 and theirlocations determines the proportion of the light input to the manifoldthat is split to each arm.

As shown in FIG. 19B, the optical manifold 1900 may include integratedoutput elements 1915. The output element 1915 may be lens-likestructures that provide lighting functions within the vehicle, such as areading lights or dashboard lights. The manifold 1900 may have multipleinput 1905 and output arms 1910 and a portion 1920 where light from thevarious inputs is combined. Each input and output may use coloredfilters to achieve desired lighting effects.

Other embodiments are within the scope of the following claims.

What is claimed is:
 1. An optical waveguide for illuminating theinterior of a cup holder in a vehicle, the waveguide comprising a pieceof solid material having: a ring portion sized and shaped to be receivedwithin a cup holder and configured to release light into the cup holder,an input face configured to receive light from a light source, and aninput portion connected tangentially to the ring portion and extendingbetween the input face and the ring portion, the input portion beingconfigured to confine light through internal reflection and to directlight from the input face to the ring portion.
 2. The waveguide of claim1, wherein the ring portion defines an inner circumference and isconfigured to release light around the inner circumference.
 3. Thewaveguide of claim 1, wherein a ratio of an inner radius of the ringportion to a width of the ring portion is greater than or equal to 3:1.4. An optical waveguide for illuminating the interior of a cup holder ina vehicle, the waveguide comprising a piece of solid material having: aring portion sized and shaped to be received within a cup holder andconfigured to release light into the cup holder; an input faceconfigured to receive light from a light source, and an input portionextending between the input face and the ring portion, and configured toconfine light through internal reflection and to direct light from theinput face to the ring portion; wherein the ring portion defines aninner circumference and has a protruding angled portion around the innercircumference, the angled portion being configured to direct light downtoward a bottom portion of the cup holder.
 5. The waveguide of claim 4,wherein an upper surface of the angled portion is stippled.
 6. Thewaveguide of claim 4, wherein an upper surface of the angled portion iscovered with an opaque material.
 7. An optical waveguide forilluminating the interior of a cup holder in a vehicle, the waveguidecomprising a piece of solid material having: a ring portion sized andshaped to be received within a cup holder and configured to releaselight into the cup holder, an input face configured to receive lightfrom a light source, and an input portion extending between the inputface and the ring portion, and configured to confine light throughinternal reflection and to direct light from the input face to the ringportion; wherein the ring portion defines an inner circumference andcomprises a first arm and a second arm that define the innercircumference with a gap in the inner circumference.
 8. The waveguide ofclaim 7, wherein the ring portion further comprises a web portion thatextends between the first and second arms, the web portion beingconfigured to release light along an edge of the web portion.
 9. Thewaveguide of claim 7, wherein the ring portion further comprises a tabthat extends from the inner circumference between the first and secondarms.
 10. The waveguide of claim 9, wherein the tab has a rectangularcross-section.
 11. The waveguide of claim 9, wherein the tab curvestoward a bottom portion of the cup holder.
 12. The waveguide of claim 9,wherein the tab has a chamfered leading edge.
 13. The waveguide of claim7, wherein the second arm has a smaller cross-section and a smallerlength than the first arm.
 14. An illuminated cup holder for a vehiclecomprising: an optical waveguide formed as a piece of solid materialhaving: a ring portion sized and shaped to be received within the cupholder and configured to release light into the cup holder, an inputface configured to receive light from a light source, and an inputportion extending between the input face and the ring portion, andconfigured to confine light through internal reflection and to directlight from the input face to the ring portion; the cup holder furthercomprising: a bottom surface, a side wall extending from the bottomsurface and defining a volume shaped and sized to receive a cup, and arim positioned around an upper edge of the side wall.